Police were called to Nowra High School on Thursday, June 13, prompting alarm on social media.
The Department of Education has released a statement at 2.50pm about an incident at the school.
"An incident involving three students took place at the school today," the statement read.
"The school was placed into lockdown, and police were called.
"At no stage were any other students or staff in danger, during the incident.
"The issue has now been resolved, and students are attending regular classes."
The department directed any other enquiries to NSW Police.
NSW Police media said no teachers or police were harmed.